Elevated prolactin responses to L-tryptophan infusion in medication-free depressed patients.

Abstract

RATIONALE:

Several previous neuroendocrine studies have demonstrated reduced 5-HT1A receptor function in major depressive disorder (MDD). However, hypercortisolaemia or previous drug treatment may have been significant confounds.

OBJECTIVES:

To replicate previous studies in subjects with MDD who had been drug free for at least 8 weeks and to relate the findings to measures of HPA axis function.

METHODS:

Hormonal responses to l-tryptophan infusion were measured in patients with MDD (n=20) and healthy controls (n=20). Basal salivary cortisol and DHEA were also profiled.

RESULTS:

No attenuation of 5-HT1A receptor-dependent neuroendocrine responses (growth hormone, prolactin) was observed in patients with MDD. The prolactin response to l-tryptophan was significantly greater in MDD patients than in healthy controls (P=0.008). There was a significant negative correlation between prolactin response and basal salivary cortisol secretion over the 3 days prior to the test.

CONCLUSIONS:

These data do not support previous findings of reduced 5-HT1A function in MDD and suggest that hypercortisolaemia or psychotropic medication may have accounted for the attenuation. Basal cortisol, DHEA and the cortiso l-DHEA ratio did not differ between patients and controls, and all patients were psychotropic medication-free. The greater prolactin response to l-tryptophan infusion in depressed subjects may be the result of an increase in dopamine receptor sensitivity, secondary to reduced dopamine levels.

• Authors: Richard J Porter, Peter Gallagher, Stuart Watson, Margaret S Smith, Allan H Young
• Journal: Psychopharmacology (Psychopharmacology (Berl)) Vol. 169 Issue 1 Pg. 77-83 (Aug 2003) ISSN: 0033-3158 [Print] Germany
• PMID: 12728300 (Publication Type: Clinical Trial, Controlled Clinical Trial, Journal Article)

Chemical References

• Receptor, Serotonin, 5-HT1A
• Dehydroepiandrosterone
• Tryptophan
• Prolactin
• Hydrocortisone

Topics

• Adolescent
• Adult
• Dehydroepiandrosterone (analysis, metabolism)
• Depressive Disorder, Major (metabolism, physiopathology)
• Female
• Humans
• Hydrocortisone (metabolism)
• Hypothalamo-Hypophyseal System (physiology)
• Infusions, Intravenous
• Male
• Middle Aged
• Pituitary-Adrenal System (physiology)
• Prolactin (blood)
• Receptor, Serotonin, 5-HT1A (physiology)
• Saliva (chemistry)
• Tryptophan (administration & dosage, blood)